Roundhouse Machine Screw Hole Help

[nachoman]

Josh - I see now. That is actually some kind of sheet metal screw that taps its own way into the pot metal frame. These were common in roundhouse kits. Some times they take a bit of force to tighten them all the way down. You have a few choices:

1) continue tightening and hope that you don't strip out the screw or crack the frame.
2) drill the hole all the way through the frame to a slightly larger size. The screw will be easier to put in, and less likely to mushroom the frame or strip out the slot on the screw. The drawback is if you enlarge the hole too much, the screw may not stay tight.
3) Buy a 2-56 tap and the appropriate drills, drill and tap a new hole, and put the coupler box on with a 2-56 screw.

I would go with #3 personally, as i already have a tap and a source of screws. I have several roundhouse kits that I did this to - especially locomotives that need to be disassembled on occasion. The 2-56 is simply easier and more reliable for repeated disassembly.